1. Field of the Invention
The present invention relates to a method for making a fiber reinforced endless or continuous laminate which can be used for manufacturing a spar cap or another part of a rotor blade of a wind energy turbine. Moreover, the present invention relates to the use of such a laminate for making structures such as a spar cap or another part of a rotor blade of a wind energy turbine.
2. Related Prior Art
Continuous laminates, i.e. endless flat panels of fiber-reinforced resin or other curable material are basically known. These laminates are produced in a continuous process by pulling tows of fibers (e.g. of glass or carbon) through a bath of resin and by forming the panel thus obtained. Within the laminates the fibers are arranged side by side and are aligned substantially parallel to each other. These continuous laminates can have a thickness between under 1 mm and up to several mm. The width of the laminate can be realised in substantially every dimension. The matrix material (e.g. resin) is cured in an endless process and the sheet-like laminate is wound up into coils with a length of a couple of hundreds of meters. These laminates are suitable to stack up parts or layers thereof for e.g. a spar cap of a blade of a wind energy turbine. As the fibers are substantially perfectly aligned and maintained in this alignment within the prefabricated laminates, the risk of fiber misalignment (to which especially the carbon fibers are very sensitive) upon arranging the individual layers of the laminate in the mould for manufacturing the blade is reduced.
Continuous fiber reinforced laminates as described above are sold e.g. by the Finnish company EXEL.
Using the continuous prefabricated fiber reinforced laminates for manufacturing a spar cap or another part of a wind energy turbine rotor blade involves an arrangement in which several layers of cut pieces of the laminate have to be arranged on top of each other in order to make a structure. These structures are arranged within specific areas and regions of a rotor blade mould in which also other sandwiched structures are placed. The spar cap and sandwich structure of the rotor blade provides for a rigid and shear-resistant overall structure which is light in weight and very stable. In order to manufacture the blade, an infusion process is used during which curable material (e.g. resin) is flowing into the mould in order to penetrate between the layers of the laminate as well as the structural members of the rotor blade. During the infusion process the laminate layers are pressed together due to a vacuum applied to the mould. Such infusion processes are also used for manufacturing other elements made from laminates. During these processes it might happen that the curable material flowing into the mould does not penetrate all the way through between the layers of the laminates. This results in an insufficient mechanical connection of adjacent layers of the laminates, and, accordingly, in a less rigid and stable structural element of the rotor blade or another part made from the fiber reinforced laminates by the infusion process.